Method of refeeding electrical discharge machining electrodes

A method of refeeding electrodes in an electrical discharge machining apparatus having a nose guide and an electrode datum movable relative to one another, a cartridge movable relative to the nose guide, a plurality of substantially parallel electrodes supported by the nose guide and by the cartridge so as to be longitudinally movable, and a cartridge clamp engageable to prevent relative motion between the electrode and the cartridge comprising the steps:

• (a) increasing separation of a datum from the nose guide, cartridge and electrodes by a predetermined distance;
• (b) advancing the cartridge relative to the nose guide by the predetermined distance, while the cartridge clamp is engaged;
• (c) decreasing the separation of the datum from the nose guide and cartridge by the predetermined distance while the cartridge clamp is disengaged to engage at least two of the electrodes with the datum so as to cause relative movement between those at least two electrodes and the nose guide and cartridge;
• and
• (d) retracting the cartridge relative to the nose guide while the cartridge clamp is disengaged.